Range finder



June 4, 1946. s. M. MacNElLLE 2,401,696

RANGE FINDER I I Filed June 23, 1945 4 Sheets-Sheet 1 I LIGHT DEV/A IFIG.1. R

Z ADJUSTER INVENTOR 41 DEVIAToIPIIQ 67 63y L! w ZERO 5 ADJUSTER 1 1 50 STEPHEN M. MACNEIILLE June}, 1946. 's. M. MacNEILLE 7 2,401,696

RANGE FINDER Filed June 23, 1943 4 Sheets-Sheet 2 LIGHT DEV/ATOR FIG.5.

ZERO ADJUSTER v FIG. 6A.-

91 r 95 UPPER HALF 91 FIG. 6B UPPER HALF saw TRANSPARENT 90 w 4; LINE FIG.6.

99 as 96 .97 1 LIGHT I 93 ggigi DEV/A'TUR 95 j 91 91 I j /:L I I STEPHEN M. MACE ILLE INVENTOR Jun 4,1946'. Y a M, N' 2,401,696-

I RANGE FINDER Filed June 23, 1943 4 Sheets-Sheet 5 13o ARIUSTER 141 142 52 52 I i 5 22 I 56 FIGJVOA. 2 i

FIG.11.

145 150 f ig 31 5 STEPHEN M NEJLLE INVENTOR.

, BY W 76-4- June 4, 1946. M, MacNElLLE 2,401,696

RANG EFINDER 'Filed June 23, 1943 4 Sheets-Sheet 4 la/iii $266 LIGHT PEV/ATOR 168 6 mnu FIGJZA.

DEV/Am? FIG. 13. V

.Range finders-Case -B UNITED STATES PATENT oFncE' Stephen M. 'MacNeille, Rochester, N. Y., assignor Eastman Kodak Company, Rochester, N. a corporation of New Jersey 1 Applicationlune 23, 1943, Serial No. 491,956

1 This invention relatesto range is Case of a series of applications relating to the same subject and including the following:

Title Filed Inventors Mount for optical elemen Range finder oonstmction. Range finders-0ase A.

461,584 Oct.

461, 585 Oct.

472, 831 Jan. 472,832 Jan. 472, 833 J an. 472, 834 Jan. 472, 835 J an.

Mar. 479, 097 Mar. 479,098 Mar. 13, 1943 Mar. 13, 1943 479, 100 Mar. 13, 1943 Mihalyi.

Do. Do.

Range finders-Case 0. Range finders-Case D- Range finders-Case E Range finders-Case F Range finders-Case G. Range finders-Case H- Range finders-Case 1-. Range finders-Case 1.. Range finders-Case K. Mar. Range finders-Case L 479, 102 Mar. Range finders-Case M. 491, 954 June Range finders-Case N- 491, 955 June Range finders-Case 0. 491,956 June 3 MacNeille. Range finders-Case P 526,020 Mar. 11,1944 Do.

Range finders- Jase T. 508, 180 Oct. 29,1943 Do.

The purpose of the present invention is to give increased sensitivity in any of the range correction setting or autooollimating systems described in the above listed cases. The present invention is useful with and described in connection with coincidence range: finders, short base range finders, ortho-pseudostereo range finders, stereo range finders, range correction setting systems, pure autocollimating systems, coincidence line and fiducial mark systems, single observer instruments, auxiliary observer instruments and in combination with the meth: ods described in Cases M and N which also give increased sensitivity. It is an object of one embodiment of the invention to give an extremely stable coincidence .line and fiducial-mark arrangement useful in either coincidence or stereo range finders.

Fundamentally, the increase in sensitivity by the present invention is gained by sending the collimator light beam, described repeatedly in other cases in this series; back through the range finder optical system for at least one extra trip. The invention is most easily described with respect to a range correction system and hence is so described although it is applicable to the other finders. This 17 Claims. (01. 88-291);

system to form an image thereof adjacent to the other element whichis in the same comparison plane or in the other one. Of course, in coincidence range finders the comparison planes are coplanar. The projecting means includes in one of the comparison planes a reflector with at least two reflecting surfaces. A triple mirror with its apex optically in the comparison plane or at least a dihedral reflector with its roof edge vertical and optically in the comparison plane is satisfactory. r Q 5 Since the element light beam-traverses the range finder optical system twice, anything which affects the light beams from the object being ranged, doubly affects theelement light beam. This results in double sensitivity and thus makes it easier to bring the range correction setting marks into coincidence.

By having at leastgtwo such reflector systems, one inea'ch comparisonplane, the element light beam may be reflected back and forth through the optical system, increasing the sensitivity in proportion to the number of trips, until ultimately the light loss is so great that'no useful image is formed. If the element light beam traverses the system aneven number of times,

the adjustment coindicant elements are. of

course, in the same comparison plane whereas they are in opposite comparison planes when the light beam makes an odd number of trips.

In combining this case with Case M itis' possible to have the relayed images viewed stereoread in connection with the accompanying drawings, in which? 7 Fig. '1 is a plan view of a coincidence range finder incorporating a simple embodiment of the invention, Fig. 1A being a view through the eyepiece of the instrument;

Fig. 2 is a schematic showing of the optical system of Fig. ,1; I r

Fig. 3 is a similar schematic showing of a somewhat more elaborate embodiment;

Fig. 4 showsan embodiment of the invention applied to stereo range finders, Fig. 4A being the binocular field of view through the instrument;

Fig. 5' shows asimilar embodiment .in. which the, element light beams originate in a third plane, and are viewed in'a fourth plane by an arrangement and Figs. .7A and 713 being. the binocular fields of view of the main'and auxiliary observers;

Fig. 8 shows the application of the invention; to a range finder of the type described in Case L of this series, Fig. 8A being the field of view;

Figs. 9 and 9A show an alternative embodiment of one detail of Fig. 4;} j W Figs. 10, 10A, 11 and 11A show alternative em bodiments of a detail of Fig. 1;

Fig. 12' shows a short base range finderincorobject, beams.

21 range finder optical system until ultimately it comes to focus forming an image 45.

In Fig. 4 light beams from the object being ranged are received by optical squares 50 and brought to focus by objectives 5| in stereo comparison planes 52 in which are located field lenses. The stereo images are viewed through optical systems including dihedral reflector 53, relay lenses 54, adjustable rhomb's 55 and eye- 5 pieces 56. The apparent object distance is ad- 'justed by a light deviator 68 located in one of the According to the invention light froma lamp 60 is reflected by a semi-transparit] entlrefiectingfsurfafce 6| to illuminate a vertical :1

mark 62..; 'I'hisma'rk itself is viewable through the semi-transparent surface 8| by the right eye 3 of the observer.:- Preferably, however, a similar porating a pure autocollimating form of the invention, Fig, 12A being the field of View;

Fig. 13,shows a stereorange finder incorporating a coincidence line and "fiducial mark form of the invention, Fig. 13A being thefield or viewof an auxiliary "observer and Fig. 133 being an enlarged view of the coincidence line'and fiducial mark element; a

Figs. 14,15 and 16jshow "a de'. "iljof a preferred embodiment of the invention which may be in corporated either in th'e'coincidnce' range finder ofFig. 1 or the'lstereorangefinder of Fig. 4.

In Fig. 1 light from the object bem ran 'ea is received. on mirrors 20 arrangd to form. optical squares and is broughtto focus by'objectives 2| and prisms 22 and 23 to form images in 00- planar comparison planes 241 to v be viewed through an eyepiece 2 5. Coincidence 'of the range finder images is adjusted by alight deviator 26 located inche of the object beams. Ac-

cording to the invention, light from a lamp 30 is reflected by prism 3! to illuminate a range correction, setting mark 32. Light from" this mark is reflected by the prism 23, collimated by the right-hand objective 2 and is picked up by small prism 33 which is not quitefan' optical square, but which'reflects the lightto a similar small prism 34 at the other viewing point of the range finder. This light is then reflected back into the optical system of the range finder and brought to focus in the comparison plane. However, just before it comes to'focus, the light strikes a porroprism 35 having its roof edge vertical and optically in the comparison plane 24, and is reflected back through the optical system, to be collimated, to be reflected from one viewing point to the other and to be brought to focus to form an image 36 adjacent, to fiducial marks 31 in the comparison plane. .As long as the, instrument stays in proper adjustment the image 36 falls between the two, diamond, shaped parts of the mark 31. If the instrument is out of adjustment for any reason, this mayv be corrected by a light deviator or zero adjuster 38 which aifects both the outgoing and returning element beam and also affects one of from the object beinglfanged.

the beams This optical system; or at least the effect there-' of is shown schematically in Fig. 2. The purpose of such a schematic showing is quite apparent when one attempts to consider more complicated systems. In fact, such a system having five times normal sensitivity is similarly ishow n in Fig. 3 wherein light from 'a lamp 4'0 reflected by a prism 4| illuminates an adjustment coindicant element 42. A pair of dihedral reflectors 43 and 44 in [the coplanar comparison "planes send this light beam 'backand forth through the and eyepieces mark located on a totally reflecting surface 61 is illuminated through the semi-transparent surface BI and light fromthis auxiliary mark is reflected bythe semi tr'ansparent surface'fil tothe observer's eye, In either case, the right "eye of the observer sees astandard mark with which he must compare an image 66, which is an image of the mark 62 produced by light collimated by the objective 5| reflected from one viewing point to the other by penta-prisms 63 and 64 and reflected back through the whole system by a porro prism 65 located in the other comparison plane. If the image 66 is not in coincidence with the original mark 62 or other standard mark 'seen with thefright; eye of 'the observer, due to malrected by means of the zero adjuster'fifl.

In Fig. 5-lightfromthe .ob'jectbe'in'g ranged -is directed ,by pentai prisms "l0 through objectives 'll into focus on field lenses 12 to be viewed as in adjustment of the instrument, this may be'cor- Fig. 4. Infthis*case,"however, the collimator strument into the range finders to'come to focus I in the comparison planesand to bereflected by ,porro prisms and .8! there located. The reflected beams are picked up bypenta .prisms 82 and 8.3 and brought to focus by a len's84 to form images185 which may. beviewed through an eyepiece 8.6,. The field of viewo'f an auxiliary observer is shown in Fig. 5A. As before, coincidence of the images 85 may :be obtained *by' adj ustinga zeroadjuster '69. Since the prisms-:18 and 19 act as .a beam splitter, the mark l6iconstitutes both .elements iof: the pair. .of adjustment coindicant elements or. the upper half of the mark 16 is one element andlthe lowerwhalfsis w n points of the instrument i'nt'othe ranges deisystem 1 and is reflected backfby porro prisms "94 positioned in the eompsrisonpia'nes; Thebeams are finally brought'to focus by the lenses 92 forming images In]. By means of totalrenecting surfaces 95, prisms 96, relay 'l'en's'es 91, prisms 98 x 99, these'imagesflfll may be viewed ie o r g l b 'ena xiiiarvio erver 'jmarks 91 are in the form oftransp'aren't"slits-in '5 "silvered surfaces. Light from the silvered area is reflected back through the" semi-transparent surface so that it is viewable directly by the auxiliary observer. The mark 9I thus appears as a dark line'on a bright ground, whereas its image appears as a bright line on a dark ground. This is shown in Fig. 7B.

In Fig. 8 the left-hand object beam is received by mirrors I20 and I28 and is brought to'focus by a symmetrical lens I22 to form an image in the comparison plane I24. The right-hand object beam is reflected by a single mirror I2I and is reflected and. focused by a semi-transparent re flector I23 symmetrically located in the lens I22. Two object images are viewed through an eye piece I25. They may be brought into coincidence by adjustment of the light deviator I32. Light from a lamp I26 is reflected by a prism I21 illuminating afiducial mark, and this-light is collimated by the lens I22, is reflected by the mirror I28 and a bevel edge I29 on the mirror I20 to strike a bevel edge I30 on the mirror I20. It is again reflected by the semi-transparent surface I23 and finally by a dihedral reflector I3I back along the whole of its path to come to focus forming an image I31 in the comparison plane I24. This image I31'f alls between two parts of a comparison mark I36 as long as the instrument is in adjustment. If it gets 'out of adjustment this may be corrected by a zero'adjuster in the form of a screw I33 for deviating the mirror I2I. As long as the instrument is in proper adjustment the calibration of the light deviator I32 is correct.

Fig.9is similar to Fig. 4 but shows a combinationof the invention with that shown-in'Case M of this series so that the resulting sensitivity is four times normal. In Fig. 9 light from lamps I40 i's'reflectedby prisms I4I to make the round trip through the range finders optical system and back again after reflection at porro prisms I42. This light comes to focus to form images I43 adjacent to the original images I43. The instrument is known to be in adjustment when the apparent image distance of the images ing the upper half of the mark I50. The double light beam then makes the round trip and is reflected back through the system by a porro prism I46 to come to focus in the comparison plane I24. This double light beam is picked up by a dihedral reflector I41 one surface of which One of the beams is I52 is semi-transparent. reflected by oneroof surface of the dihedral reflector and the other is transmitted through the surface I52 and is totally reflected by reflector II and then reflected by the surface I52 parallel E65 to the otherbeam. As long as the instrument is in adjustment these two beams are incoincidence. Both beams are reflected by the surface I53 to the eyepiece 25 Any maladjustment of the instrument afiects the outgoing pair of beams and similarly affects the returning pairof beams to give double sensitivity. The dihedral reflector pick-up system consisting mainly of the porro prism I41 again doubles the sensitivity since the --relative movement of the two beams is twice that I43 appears to be the same as the apparent element .6 of either beamalone. Thus, the resultant sensitivity is four times normal.

Fig. 11A shows an alternative embodiment in which both the upper and lower halves of the mark I are deviated by rhombs I 45 and I54 respectively.

In Fig. 12 is shown an embodiment of the invention applied to short-base range finders particularly applied to pure autocollimation as distinguished from range correction setting. These features are alternative in most embodiments ofthe invention.- In this Fig. 12 the viewing point mirrors I and IE1 send light through a lens I62 into focus in a comparison plane I63 to be viewed through an eyepiece I64. Light from a lamp I65 illuminates a mark I66 and this light is collimated by the objective I62, is reflected by an auxiliary reflector I61 on the mirror I60 and is then reflected by a prism I68, equivalent to a 'dove prism, rigidly attached to the mirror I6I.

This light is brought to focus by the objective I62 approximately in the comparison plane I63 whereat it is reflected by a porro prism I69 back through the whole optical system eventually to form an image I66 at the comparison plane I63,

which image acts as an index for a scale I1I engraved in the comparison plane. The double sensitivity feature in this case permits the scale -I1I to be larger, and hence, more .easily read. Coincidence of the object images is obtained by adjustment of a light deviator I10 operating on the mirror I60.- Anything which affects the coincidence of the object images, similarly aifects line and fiducial mark each consisting of a spiral I19 on a disk I18 areilluminated. Light from these'adjustment coindicant elements I19 is collimated by lens I and one half of it is reflected by a mirror IBI through lens II 'to a porro prism I84 in the comparison plane 52 and thence back through the objective H which collimates the light again. The collimated beam is then reflected by a mirror I82 to' an objective I185 which brings it into focus in an auxiliary comparison plane I86 to form' an image I19. The other beam is first reflected by the mirror I82 to the left-hand viewing point and by penta prisms I83, from one viewing point to the other and into the right-hand half of the range finder. The beam is then reflected by a porro prism I84 in the right-hand comparison plane back around the system until it strikes the mirror I8I which reflects it to the lens I85 and eventually into focus to form the other image I19. The :main observer varies the apparent object distance, by means of a light deviator I15, to match some standard reticle, not shown. At the same time the auxiliary observer rotates the disk I18 until the-i'mages I19 as shown in Fig. 13A are brought into coincidence. At this time the range This arrangement gives the advantages of apoincidence line and flducial mark system and in Fig.- 1 gives the'doublesensitivity'due to the agoncoo present invention. Considering it first in connection with Fig. 1, afield lens -.or other unit "I99 is placed in the comparison plane 24 ito be rotatable about its center, approximately at which point is rotated the apex of a-triple mirror I94, rigidly mounted to rotate with the element I90. Light from a lamp I9I reflected by asemi-transparent surface I98 illuminates spiral 192 chgraved on the element I90 and this light quakes the round trip shownin Fig. 1 until it strikesxthe triple mirror I94, which replaced the porro'prism 35 of Fig. 1, whereat it is reflected back'around the whole optical system to form an image I95 adjacent to the spiral I92. .Both the spiral. or at least the illuminated portion thereof, and :the image I95 are viewable through the eyepiece 25. When the object images are brought :into coincidence by a light deviator at theposition oi the zero adjuster 38, the light deviator 26 being eliminated in a coincidence linessystempthe disk or element I 99 is rotated untilthe image I95 and line I92 are in coincidence, at which (time the range may be read by a scale I99, carried by the element I99, against an index I91.

The same is true when the element I 99 .is substituted for the element 52 of Fig. 4. That is, the light deviator 68 is no longer necessary 'and is replaced by one at the position :of the zero adjustor 69, the range being :given :by a .scale I98 operated by the coincidence line 192. Attention is drawn to the fact that the fiducial mark for the coincidence line I92 is-the image of the line itself and this is made possible by the use of the present invention consisting of a triple mirror I94 (replacing 35 in Fig. 1 and cooperating with 95 in Fig. 4) in the other comparison plane. Further, the triple mirror I94 is :rigidly attached to the coincidence line I92 so no "error can be introduced by looseness in'the bearings supporting element I99. This is of, course offlgreatest value in the coincidence type range finder in Fig. 1, but in Fig. 4 it gives four-times sensitivity instead of double sensitivity since two reflectors, namely, I94 and 65, both operate on the element light beam.

What I claim anddesire to secure by Letters Patent of the United States is:

1. A range finder of the type having two horizontally spaced viewing points at which beams of light are received from :the object being ranged, an optical system for focusing the object beams to form images in comparison planes and .a ranging adjustor operating effectively horizontally, said range finder being characterized by a pair of adjustment coindicant elements and means for projecting at least twice through said optical system .a .light'beam from one of the elements to form an image thereof adjacent to at least an image :of the other element, said projecting means including a reflector with at least two reflecting surfaces at one comparison plane .for receiving the element beam, and for reflecting it back through the optical system to the other comparison-plane.

2. A range finder according to claim 1 'in which said projecting means includes another reflector with two reflecting surfaces at the other comparison plane so that the element beam traverses the optical system at least three times.

3. A range finder according to claim 1 and of the coincidence type in which the comparison planes are coplanar. M

4. A ranger finder according to claim .1 'in which the adjustmentcoindicant elementsarea .fiducial mark. and coincidence line respectively.

fleeting it back through said optical system to the other comparison plane. I

'7. A range finder according to claim 1 in which'said reflector is a right angle porro prism with itsroof edge in said one comparison plane.

8. The subcombination according to claim 6 in which said pair of reflecting surfaces are the sides .of a porro prism with its roof edge inIs'aid one comparison plane.

9. A range finder according to claim 1 in i which said reflector is a triple mirror system with its apex in said one comparison'plane.

10. In an autocollimating range finder of the type in which an image of one adjustment coin-' dicant element is formed adjacent to another by lighttraversing the optical system of the range finder, the subcombination of a triplemirror at one comparison plane of the range finder for receiving said light, for displacing it effectively horizontally and for reflecting it back through said optical system.

11. A ranger finder of the type having two horizontally spaced viewing points at I which beams of light are received from the object being ranged, an optical system for focusing the object beams to formimages in comparison planes and a ranging adjustor operating efiective'ly hor1- zontally, saidrange finder being characterized by a pair of adjustment coindicant elements,'means for projecting through the optical system a light beam from each element to form an image'approximately in each comparison plane 'respectively, a reflector with at least two reflecting surfaces at each comparison plane for receiving each beam, for displacing it efiectivelylho'rizontally and for reflecting it back through the optical system to form r'elayedelement imagesa'nd means for viewing the relayed images'relatlve to one another. v

12. A range finder according to claim 1 1'in which the relayed images and the elements are all viewed stereoscopically to give apparente'lement and image distances. 7 I p 13. A ranger finder of the type "having two horizontally spaced viewing points at which beams of light are received from the object being ranged, an optical system forfocusing the object beams to form images in comparison planes and a ranging adjustor operating effectively hori zontally, said range finder being characterized by a pair of adjustment coindic'ant elements and means for projecting through at least half of said optical system a light beam from one of the elements to one of the comparison "planes and back through said at least half of the "optical system to form an'image of the elementior comparison with at least an image of the-other element, said projecting means including a redoctor with at least two reflecting surfaces at said one of the comparison planes .tor receiving said beam, for displacinglit effectively :liorizontally and for reflecting it back. H 14. .A ranger finder accordingto claim :13 in which said one of the elements it at last optically in the other comparison plane and the projecting means includes the whole of the optical system. 7

15. A range finder according to claim 13 in which said projecting means includes only said half of the optical system and a similar projecting means is in the other half of the optical system to form an image of the other element for comparison with the image of the first mentioned element.

16. A range finder according to claim 13 ineluding another reflector with two reflecting surfaces for receiving the reflected beams, for 

